Communication within an interactive two-way broadcast data service network is described in detail in U.S. Pat. No. 5,388,101, by G. Dinkins, entitled "Interactive Nationwide Data Service Communication System For Stationary And Mobile Battery Operated Subscriber Units." In such a system, a local base station repeater cell transmits digital data to individual low-cost, portable, battery-operated, milliwatt transmitter, subscriber units within a local base station designated area. A plurality of receive only stations, remote receivers, are distributed throughout the local base station designated area and are connected by wire, cable, microwave link, or radio to the local base station repeater cell. The remote receivers are referred to as receive only stations because they receive signals from the subscriber units but do not transmit signals to the subscriber units. The remote receivers process and relay transmitted digital data received from the individual subscriber units. Thus, the local base station repeater cell transmits data directly to the individual subscriber units. The milliwatt transmitter individual subscriber units, however, do not transmit data directly back to the local base station repeater cell. Instead, the individual subscriber units transmit to a remote receiver which then relays the data to the local base station repeator cell. The use of remote receivers allows the individual subscriber units to transmit data signals using power in the milliwatt range.
Unfortunately, under certain conditions, individual subscriber units are unable to receive transmissions from the local base station repeater cell. For example, a user may purchase a subscriber unit and place the subscriber unit in, for example, a basement or other physical location which prevents the subscriber unit from receiving transmissions from the local base station repeater cell. Likewise, the subscriber unit might be placed in a location such as, for example, a building with concrete walls which substantially weaken the intensity of the rf signals received by the subscriber unit.
In an attempt to alleviate reception problems, local base station repeater cells have been situated with overlapping coverage to produce strong signals throughout a given area. However, such placement of local base station repeater cells is extremely costly due to the number of local base station repeater cells required, and such "crowded" placement of the local base station repeater cells is not always practical. In a further attempt to deal with ineffective communication between the local base station repeater cell and the subscriber unit, the location of the user is determined at the time of sale of the subscriber unit to the user. However, even if the user's location is within an area with strong local base station repeater cell coverage, the subscriber unit might still be placed in a physical location which weakens rf signals or completely prevents the subscriber unit from receiving rf signals from the local base station repeater cell.
Thus, the need has arisen for a system to provide for effective transmission of data signals from a local base station repeater cell to subscriber units in areas where such communication has previously been impaired, which provides for the reception of strong rf signals at the subscriber units, which does not require the addition of numerous costly local station repeater cells, which is not dependent on the physical location of the subscriber unit, and which does not significantly increase the cost of communication within the interactive two-way broadcast data service network.